Justin is among the first of the apologists of the church. He studied philosophy extensively--Platonism, Stoicism, and others--and eventually came to the conclusion that Christianity was the best school of thought. He argued for the marrying of philosophy and religion, even asserting that many philosophical ideas (like the immortality of the soul) actually came from Jewish Scripture. In my opinion, that's a bit misguided since as far as I know the Jewish Scriptures don't teach or assume the immortality of the soul at all. But anyway.

Justin went so far as to say that Socrates was a Christian, because he lived by reason--the Logos which would come into the world and by which Christians also live. Justin was especially focused on God as this Logos.

The Apologies were the beginning of a long tradition of mashing up philosophy and Christianity and asserting that Christianity is really based on reason. Tertullian would take issue on this later, saying "What has Athens to do with Jerusalem?" Justin Martyr is like a really really early forerunner of CS Lewis.

The reigning Hellenistic government of the time, headed by Marcus Aurelius, didn't see eye to eye with Justin or the Christians though, confused by the fact that they refused to worship the emperor and therefore seen as "atheists"--since the "God" they said to worship didn't seem to exist.

Justin and Friends were questioned and ultimately beheaded in about 165.

What you should read:

Ratings:
(To read more about my Theologian Rating System, click HERE)
Gender Equality:

With Justin's emphasis and love for the classic philosophers, I'm certain that he did not escape their influence in regard to hating women. Especially with his propensity for Platonic thought.
Environmental Sensibility:

Along the same lines as his views toward women, I believe that Platonic ideals and even Stoicism are rather harmful to any sort of appreciation for the Earth--they lead the person to value the mind and the "spirit" over above the body, or indeed nature as it is.
Heretical Tendencies:

I think Justin's beliefs are fairly orthodox--even (or maybe especially) today. He is considered a saint in both the Roman Catholic and Greek Orthodox churches.
General Badassery:

He was very well educated, wrote a ton, and had a huge part in the way the church relates to philosophy. He may not have faced any wild beasts, but martyrs get four stars by default.

A Justin Martyr quote to finish:

"We pray for our enemies; we seek to persuade those who hate us without cause to live conformably to the goodly precepts of Christ, that they may become partakers with us of the joyful hope of blessings from God, the Lord of all."